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Aluseg and the Portuguese Tax Authority (AT)

On paid plans, Aluseg registers your tenancy agreement with the AT and issues electronic rent receipts on your behalf. See what data is sent and how we protect your password.

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  • AT's official webservice
  • Password encrypted AES-256-GCM
  • Receipts in your own Portal das Finanças
Person reviewing a tenancy agreement at a desk

The essentials

What Aluseg does with the AT

All of this runs through the AT’s official lease communication and rent receipt webservice for software producers. Aluseg is provided by Quotidiano Tagarela Unipessoal Lda (NIPC 517944456), registered with the AT as a software producer.

  • Lease registration

    The filing that replaces the old Modelo 2, using the data already in Aluseg.

  • Electronic rent receipt

    Issued for each month, once the rent is recorded as paid.

  • Receipt PDF retrieval

    Archived in your workspace and your tenant's.

  • Mutual TLS connection

    A software-producer certificate identifies Aluseg to the AT on every request.

Data sent

What data is sent

Only what the law and the webservice require for the lease and each receipt: the landlord’s and tenant’s NIF, the property identification (artigo matricial), dates and rent amount. The AT receives it as a public authority, under the landlord’s legal obligation to register leases and issue rent receipts.

Why we need your password

Two authentication layers on every request

The AT webservice has no delegated-authorisation system (no “sign in with” option).

  1. 1

    Software-producer certificate

    Identifies Aluseg to the AT through a mutual TLS connection.

  2. 2

    Taxpayer NIF and password

    Identify the landlord issuing the document; the password is encrypted inside the request with the AT's public key (RSA + AES).

  3. 3

    Request processed

    The lease is registered or the receipt is issued directly in your Portal das Finanças.

Security

How we protect your password

Your Portal das Finanças password is treated with the same care as a banking secret.

  • Encrypted at rest

    AES-256-GCM; the key lives only in the server environment, never in the database.

  • Not readable by the app

    The encrypted column cannot be read by your session or anyone else's.

  • Decrypted only in memory

    Only at the moment an AT request needs it.

  • Deletable at any time

    In Settings › Tax, delete your credentials and Aluseg immediately stops making requests to the AT.

Check and disconnect

Full control over the connection

  • Check

    • Log in to the Portal das Finanças, go to Arrendamento.
    • Confirm the registered lease and issued receipts.

  • Disconnect

    • In Aluseg, go to Settings › Tax and delete your credentials.
    • They are deleted immediately and no further requests are made to the AT.

  • Change password

    • If you change it in the Portal das Finanças, just enter the new one in Aluseg.

Plans

Current status and plans

AT integration is included in the plans that issue AT receipts (Essential and above).

Feature Free Essential Expert
Lease registration and AT receipts No Yes Yes
Plan price €0 €7/month or €60/year, VAT included, up to 5 properties €25/month or €199/year, VAT included, up to 20 properties

Available since September 2026; the production connection was validated with the AT in August 2026. Page last reviewed: 27 September 2026. See also the Platform Privacy Policy, pricing and Aluseg facts.

Frequently asked questions

Tax Authority (AT)

Does Aluseg use an official AT system?

Yes. We use the AT’s official webservice for lease communication and rent receipts, available to software producers, with a software-producer certificate.

Why do I have to give my Portal das Finanças password?

Because the AT webservice requires every request to be authenticated with the taxpayer’s NIF and password; there is no delegated authorisation for this service. The password is encrypted, used only at the moment of the request and can be deleted at any time.

Do the receipts appear in my Portal das Finanças?

Yes. Receipts are issued at the AT in your name and appear in your Portal das Finanças, just as if you had issued them manually.

Can I stop using the AT connection?

Yes. Delete your credentials in Settings › Tax and Aluseg immediately stops making requests to the AT. You can keep issuing receipts manually in the Portal das Finanças.

Is it included in the free plan?

No. AT integration is included in Essential (up to 5 properties, €60/year, VAT included) and Expert (up to 20 properties, €199/year, VAT included).

For information only; not legal or tax advice. See also the Platform Privacy Policy and pricing. Page last reviewed: 27 September 2026.

Let your rent receipts issue themselves

Lease registration, electronic receipts and SEPA collection from €60/year, VAT included. Start free, no card needed.

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Satisfied landlord at the office, free of receipts and paperwork